The present invention relates to a driving device for a solenoid valve having a valve element to be driven by an electromagnetic force, and more particularly to such a solenoid valve driving device for two adjacent solenoid valves.
It is known that an intake valve and an exhaust valve of an internal combustion engine are configured by solenoid valves each having a valve element to be driven by an electromagnetic force. To minimize the power required to drive such an electromagnetically driven intake valve or exhaust valve, increasing the sectional area of a magnetic circuit in a driving device for driving the solenoid valve is effective. However, such an increase in the sectional area causes an increase in size of the driving device. For example, in the case that two intake valves and two exhaust valves are provided in one cylinder, a mounting space for the driving device is lacking. Japanese Patent Laid-open No. 9-256826 has proposed a solution for this problem such that the contact surfaces of two adjacent driving devices are made flat to thereby reduce the distance between the two adjacent driving devices, thus allowing the driving devices to be mounted at an upper portion of an internal combustion engine.
In the case of operating two adjacent intake valves, for example, the two adjacent intake valves are normally operated at the same timing, so that it is assumed that magnetic fluxes generated in the two adjacent driving devices may interfere with each other. However, this point is not considered at all in the above publication. Thus, there is still room for improvement in the device according to the above publication from the viewpoints of further reduction in size of each driving device and further reduction in power consumption.